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Dephosphorylation of cardiac proteins in vitro – a matter of phosphatase specificity
Author(s) -
Husberg Cathrine,
Agnetti Giulio,
Holewinski Ronald J.,
Christensen Geir,
Van Eyk Jennifer E.
Publication year - 2012
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.201100116
Subject(s) - dephosphorylation , phosphatase , phosphorylation , biochemistry , proteome , kinase , biology , alkaline phosphatase , cytosol , enzyme , microbiology and biotechnology
Protein phosphorylation is reversibly regulated by the interplay between kinases and phosphatases. Recent developments within the field of proteomics have revealed the extent of this modification in nature. To date there is still a lack of information about phosphatase specificity for different proteomes and their conditions to achieve maximum enzyme activity. This information is important per se, and in addition often requested in functional and biochemical in vitro studies, where a dephosphorylated sample is needed as a negative control to define baseline conditions. In this study, we have addressed the effectiveness of two phosphatases endogenously present in the heart (protein phosphatases 1 and 2 A ) and two generic phosphatases (alkaline phosphatase and lambda protein phosphatase) on three cardiac subproteomes known to be regulated by phosphorylation. We optimized the dephoshorylating conditions on a cardiac tissue fraction comprising cytosolic and myofilament proteins using 2 DE and MS . The two most efficient conditions were further investigated on a mitochondrial‐enriched fraction. Dephosphorylation of specific proteins depends on the phosphatase, its concentration, as well as sample preparation including buffer composition. Finally, we analyzed the efficiency of alkaline phosphatase, the phosphatase with the broadest substrate specificity, using T i O 2 peptide enrichment and 2 DLC ‐ MS / MS . Under these conditions, 95% of the detected cardiac cytoplasmic‐enriched phospho‐proteome was dephosphorylated. In summary, targeting dephosphorylation of the cardiac muscle subproteomes or a specific protein will drive the selection of the specific phosphatase, and each requires different conditions for optimal performance.